Method of making ignition coils

ABSTRACT

A METHOD OF MANUFACTURING IGNITION COILS. A FIRST ELECTRICAL CONDUCTOR IS POSITIONED ON THE INNER SURFACE OF A HOLLOW INSULATING FORMER, AND A SECOND ELECTRICAL CONDUCTOR IS POSITIONED ON THE OUTER SURFACE OF THE FORMER. THE FIRST AND SECOND CONDUCTORS ARE SECURED TO THE FORMER, AND ARE ELECTRICALLY INTERCONNECTED BY MEANS OF AN ELECTRICALLY CONDUCTIVE FASTENING DEVICE WHICH ENGAGES BOTH THE FIRST AND SECOND CONDUCTORS AND WHICH PASSES THROUGH THE WALL OF THE FORMER. A CORE IS INSERTED INTO THE FORMER SO THAT THE CORE AND THE FIRST ELECTRICAL CONDUCTOR ARE ELECTRICALLY INTERCONNECTED. ONE END OF A WIRE IS ELECTRICALLY CONNECTED TO THE SECOND CONDUCTOR SO THAT THE WIRE AND THE CORE ARE ELECTRICALLY INTERCONNECTED THROUGH THE FIRST AND SECOND CONDUCTORS AND THE FASTENING DEVICE, AND THE WIRE IS THEN WOUND ONTO THE FORMER TO CONSTITUTE ONE OF THE WINDINGS OF THE IGNITION COIL.

Oct. 5, 1971 w, FRY ETAL 3,609,833

METHOD OF MAKING IGNITION COILS Filed Oct. 3, 1969 INVE NTOR M/a'm Ida CI r mgab swn By J 7 'A'r'ro NEYS United States Patent Oifice 3,609,833 Patented Oct. 5,, 1971 3,609,833 METHOD OF MAKING IGNITION COILS William Lawrence Fry, Haughton, and Joseph Sidney Muddiman, Birmingham, England, assiguors to Joseph Lucas (Industries) Limited, Birmingham, England Filed Oct. 3, 1969, Ser. No. 863,502 Claims priority, application Great Britain, Oct. 14, 1968, 48,520/ 68 Int. Cl. H01f 7/06 US. Cl. 29-605 Claims ABSTRACT OF THE DISCLOSURE A method of manufacturing ignition coils. A first electrical conductor is positioned on the inner surface of a hollow insulating former, and a second electrical conductor is positioned on the outer surface of the former. The first and second conductors are secured to the former, and are electrically interconnected by means of an electrically conductive fastening device which engages both the first and second conductors and which passes through the wall of the former. A core is inserted into the former so that the core and the first electrical conductor are electrically interconnected. One end of a wire is electrically connected to the second conductor so that the wire and the core are electrically interconnected through the first and second conductors and the fastening device, and the wire is then wound onto the former to constitute one of the windings of the ignition coil.

This invention relates to a method of manufacturing ignition coils.

A method according to the invention includes the steps of, positioning a first electrical conductor on the inner surface of a hollow insulating former, positioning a second electrical conductor on the outer surface of the former, securing the first and second conductors to the former and electrically interconnecting the first and second conductors, by means of an electrically conductive fastening device, inserting a core into the formerso that the core and the first electrical conductor are electrically interconnected, electrically interconnecting one end of a wire and said second conductor, so that said wire and said core are electrically interconnected, and winding said wire onto the former to constitute a winding of the ignition coil.

One example of the invention is illustrated in the accompanying drawings wherein FIG. 1 is a side elevational view of a coil former assembly, FIG. 2 is an end view of the assembly shown in FIG. 1, and FIG. 3 is a sectional view on the line 33 in FIG. 1.

Referring to the drawings, a cylindrical tube of insulating material is cut to the required length to constitute a former 11 for the windings of an ignition coil. A short length 12 of thin gauge conductive strip is inserted into the former 11 so that it lies in contact with the inner wall of the former 11. A length of copper braid 13 is then engaged with the outer wall of the former 11 so that a portion of the wall of the former 11 is sandwiched between the braid 13 and the conductive strip 12. A U-shaped wire staple 14 is then used to secure the strip 12 and the braid 13 to the former 11, the two limbs of the U-shaped staple 14 passing through the wall of the former 11 and the strip 12 and being bent over to engage 14 interconnecting the two limbs thereof engages, and

traps the braid 13 in contact with the outer surface of the former 11. Thus, the Wire staple 14 serves to secure the braid 13 and the conductive strip 12 in position, and further serves to electrically interconnect the braid 13 and the conductive strip 12.

The conductive wire staple 14 is so positioned that the portion of the staple interconnecting the two limbs thereof extends parallel to the axis of the former 11, so that there is no need for the portion of the staple, which interconnects the two limbs thereof, to be curved to ensure that the braid 13 is trapped. The tool used to staple the braid 13 and the conductive strip 12 to the former 11 is of substantially conventional form, with the exception that the anvil against which the limbs of the staple 14 are forced to bend the limbs of the staple 14, is such that it can be inserted into the former 11.

A preformed conductive core (not shown) is then inserted into the former 11 and the arrangement is such that the core is an interference fit within the former 11, so that the core makes electrical contact with the conductive strip 12. Thus the core and the copper braid 13 are electrically interconnected through the staple 14 and the conductive strip 12.

A wire (not shown) which is to form the secondary winding of the ignition coil is then electrically connected to the copper braid 13, and is then wound onto the former 11 to constitute the secondary winding of the coil. Thus, the secondary winding of the coil is electrically connected at one end to the core of the ignition coil. The primary winding is then wound on top of the secondary winding.

Adjacent layers of the secondary winding and the primary winding, and the secondary and primary windings are separated from one another in the usual manner, by layers of insulating paper. Moreover, the wire used to form the secondary and primary windings has a coating of insulating varnish, which ensures that adjacent convolutions of the windings are insulated from one another.

The assembly comprising the core, the former, and the windings is then inserted into a conventional ignition coil casing and the appropriate electrical connections are made between the primary and secondary windings and terminals on the casing, and between the core and the high tension output terminal on the casing.

Having thus described our invention what we claim as new and desire to secure by Letter Patent is:

1. A method of manufacturing an ignition coil including the steps ofpositioning a first electrical conductor on the inner surface of a hollow insulating former, positioning a second electrical conductor on the outer surface of the former, securing the first and second conductors to the former and electrically interconnecting the first and second conductors, by means of an electrically conductive fastening device, inserting a core into the former so thatthe core and the first electrical conductor are electrically interconnected, electrically interconnecting one end of a wire and said second conductor, so that said wire and said core are electrically interconnected, and winding said wire onto the former to constitute a winding of the ignition coil.

2. A method as claimed in claim 1 wherein said first conductor is a length of conductive strip.

3. A method as claimed in claim 1 wherein said second conductor is a length of conductive braid.

ing device is a conductive, U-shaped staple the limbs of which extend through the wall of the former.

5. A method as claimed in claim 1 wherein said first conductor is a length of conductive strip, said second conductor is a length of conductive braid, and said fastening means is a conductive, U-shaped staple, the limbs of said staple extending through the wall of the former and the strip and being deformed within the former to engage the strip, the portion of the staple interconnecting the limbs of the staple trapping the braid against theouter surface of the former, and said portion of the staple being disposed parallel to the axis of the former.

i i? References Cited 7 7 UNITED STATES PATENTS" 2,752,596 7/1956 McMullen. 3,277,417 10/1966 Rechel 336-192 3,437,966 4/1969 Tolley 336192 X JOHN F. CAMPBELL, Primary Examiner C. E. HALL, Assistant Examiner 

